Occurrences of the LiverwortFrullania selwynianain the Superior National Forest, Minnesota: Overlooked or Recovered?

Abstract

Frullania selwyniana Pearson was historically recorded from only two localities in Minnesota, and was last seen in 1925. The species became listed on the Region 9 Sensitive Species List (USDA Forest Service 2007) as it is a North American endemic and rare throughout its range. We recorded it in 2001 on the Superior National Forest during a Forest-wide baseline bryophyte inventory. During a dedicated survey in 2008 throughout the Superior National Forest and adjacent areas we have now located 165 populations within 19 widely separated forested stands. Most of the sites are within highly paludified white cedar swamps (i.e., with significant Sphagnum cover). However, several records are from cedar trees in ecotones between upland and lowland cedar mesohabitat, or in mixed hardwood-conifer or shrub-conifer swamps. It appears that the patches tend to be found on the upward-facing bark of leaning trees, usually directed toward some canopy opening. In addition to being overlooked inland from the shore, it has apparently recovered quite dramatically from its earlier restricted occurrence of nearly a hundred years ago. Most likely this is related to the recovery and aging of white cedar stands after restrictions to earlier logging practices went into effect.